America's first black president, Barack Obama, attacked President Donald Trump as a failure during his speech on the third night of the all-online Democratic convention.
Obama said that on handing over the White House to Trump in 2017, he thought the Republican "might show some interest in taking the job seriously; that he might come to feel the weight of the office and discover some reverence for the democracy that had been placed in his care."
"But he never did," Obama said, according to excerpts of his speech released early.
As a result, Trump has left America's "worst impulses unleashed, our proud reputation around the world badly diminished, and our democratic institutions threatened like never before," Obama said.
Trump responded by telling reporters that Obama had been "a terrible president."
Much focus was on Obama, who took a back seat during the Democratic primaries but is now throwing his still considerable sway behind Biden's campaign.
"Tonight, I am asking you to believe in Joe and Kamala's ability to lead this country out of dark times and build it back better."
Obama was speaking two days after his wife, Michelle Obama, opened the convention with a scathing takedown of Trump as "the wrong president for our country."
"He cannot meet this moment," she said.
Trump has chosen the White House South Lawn as the location for his acceptance speech -- a controversial decision given that presidents are legally required to separate their campaigning from taxpayer-funded governing.